<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ES6语法功能简单介绍</title>
</head>
<body>

<h4>重复定义</h4>
<script>
    var i=0;
    switch (i) {
        case 0:
            let value="hello";
            break;
        case 1:
            let value="world";//重复定义错误
            break;
    }
</script>
</body>
</html>
